Vectronics VEC-1120K - Manual (Page 31)

VEC-1120K/1130K/1140K/1180K Instruction Manual
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You can “prove” the LO is working by listening for its signal on a monitor
receiver. See if this general checklist helps isolate your problem:
1. Does not turn on: Check battery condition, snap clip, and power leads.
Also, make sure lead polarity is correct (red to +, black to GND). Make sure
power switch is “on”. Check operating voltages.
2. Turns on, does not receive signals: Check antenna, antenna lead, and plug
for shorted or open condition. Also, radio may not pick up signals in metal
building without an outdoor antenna.
3. Drifts off-frequency rapidly, “motorboats”, weak audio: Symptoms of a
weak battery or insufficient operating voltage. Be sure to check battery
voltage “under load” (with the radio turned on).
4. Poor sensitivity: Look for antenna problems.
Quick voltage checks:
Pin 8 of U1 (NE602) 5.0 volts
Pin 6 of U3 (LM386) 9.0 volts (battery voltage)
Pin 5 of U3 (LM386) 4.5 volts, no signal (about ½ battery voltage)
Pin 7 of U1 (NE602) 80-mV RMS RF oscillator voltage
If all else fails, and factory service is needed, consult the warranty information at
the beginning of the manual.